1. Field
The present invention relates to a method and system for adjusting a gear map.
2. Description of the Related Art
A conventional automobile with a conventional transmission generally has a few discrete gears, each of which has its own gear ratio. Thus, the transmission can operate using only a few discrete gear ratios. The gear ratios change the torque multiplication between the prime mover, typically an internal combustion engine, and the wheels. The resultant wheel torque divided by prime mover torque is the gear ratio. A similar multiplication of prime mover speed occurs. The automobile switches between the discrete gear ratios by changing gears. Thus, a change in gears to achieve a desired increased torque multiplication results in a rise in prime mover speed. Note that although prime mover torque output might change, and thus wheel torque will be variable based upon driver demand, the speed ratio between the prime mover and vehicle speed remains the same. As a result, the driver anticipates engine speed increasing at a specific rate with increasing vehicle speed while the automobile stays in the same gear.
Besides multiplying torque for acceleration, fixed gear ratios are also used to reduce engine speed to improve fuel economy. Typically, the number of gear ratios included in a transmission is a compromise between fuel efficiency, performance, driveability, and cost. Thus, a conventional transmission has a fixed number of gears in the gear map, fixed locations of the gears in the gear map, and a fixed gear ratio for each of the specific gears in the gear map.
A conventional continuously variable transmission was developed to address fuel efficiency. Unlike a conventional transmission, the conventional continuously variable transmission has an infinite number of gear ratios available in the gear map. Thus, there are no specific gears that the conventional continuously variable transmission uses to determine the gear ratio. Whereas, the gear ratio that the conventional continuously variable transmission operates at is largely dependent on the required automobile speed and the desired efficiency of the automobile.
The drawback is that the user may not be able to anticipate the engine speed for a specific automobile speed because no specific gears are used. This can be undesirable to some users. Thus, although the conventional continuously variable transmission can be more fuel efficient than the conventional transmission, some users may have difficulty adjusting to the unexpected engine speed used for a specific automobile speed. In addition, the conventional continuously variable transmission may still provide a fixed driving experience, since the user is unable to choose the engine speed for the specific automobile speed. For example, the user may not approve of the specific engine speed utilized by the conventional continuously variable transmission for the specific automobile speed as selected by the manufacturer. Thus, the conventional continuously variable transmission may still be inadequate for the user.
Thus, there is a need for a method and system for adjusting a gear map.